OK STH-4.2m² Walk-in Constant Temperature and Humidity Chamber

Overview

The OK STH-4.2m² Walk-in Constant Temperature and Humidity Chamber is an engineered environmental test infrastructure designed for system-level validation under precisely controlled thermal and hygrothermal conditions. Unlike benchtop or upright chambers, this walk-in unit functions as a fully accessible, room-scale test environment—enabling direct human entry for instrument setup, sample integration, in-situ monitoring, and intervention during extended test cycles. Its operational principle relies on closed-loop feedback control of air temperature and relative humidity via integrated refrigeration, electric heating, steam humidification (or ultrasonic/humidifier-based systems), and high-efficiency air circulation. The chamber complies with fundamental requirements of ISO 16750-4 (road vehicles), IEC 60068-2-1/2/14/30 (environmental testing), and supports test protocols aligned with MIL-STD-810H Method 502.7 (low temperature), Method 501.7 (high temperature), and Method 507.6 (humidity). It serves as a foundational platform for reliability qualification where physical scale, thermal mass, and operational complexity preclude use of smaller enclosures.

Key Features

• Modular structural design using 100 mm thick double-skin steel panels with ≥35 kg/m³ density polyurethane (PU) insulation—achieving thermal conductivity ≤0.022 W/(m·K) and minimizing heat leakage.
• Reinforced load-bearing steel frame supporting ceiling-mounted evaporator units, ducted air distribution, and safe personnel ingress/egress.
• Cascade refrigeration system with separate high- and low-stage compressors (R404A/R23 or R507/R23 alternatives), enabling stable operation down to −70°C without cryogenic consumables.
• Programmable temperature ramping from 1.0 to 4.0°C/min across the full operating range, with optional LN₂ injection for accelerated cooling profiles (upon specification).
• Integrated humidity control subsystem offering 20–98% RH at ambient to +85°C, featuring PID-controlled steam generator with stainless-steel water reservoir and automatic drain cycle.
• Industrial PLC-based controller with 10.4″ TFT-LCD HMI, supporting up to 99 programmable segments, 1000-step profiles, and real-time graphical display of all monitored parameters.
• Comprehensive safety architecture including overtemperature cutoff, refrigerant pressure monitoring, door interlock, condensate overflow protection, and emergency power-off circuitry.

Sample Compatibility & Compliance

The chamber accommodates large-format test articles—including complete automotive battery packs (up to 2.5 m tall), server racks, photovoltaic inverters, aerospace avionics enclosures, and multi-unit production batches. Its internal volume of 4.2 m³ (1500 × 1800 × 1500 mm) ensures adequate clearance for laminar airflow around thermally active devices under test (DUTs). All electrical penetrations utilize hermetic feedthroughs rated IP65; optional 100 mm diameter test ports (with silicone gaskets) maintain environmental integrity while permitting signal/power cabling. The system meets mechanical and electrical safety standards per GB/T 19001–2016 (ISO 9001), GB 4793.1–2019 (IEC 61010-1), and is compatible with GLP/GMP documentation workflows through configurable audit trail logging (user login, parameter changes, profile execution, alarm events).

Software & Data Management

The embedded control system records time-stamped temperature and humidity data at user-defined intervals (1 s to 60 min resolution), storing up to 12 months of continuous history internally. Data export is supported via USB flash drive (CSV format) or Ethernet TCP/IP interface for integration into enterprise LIMS or MES platforms. Optional software packages provide remote web-based monitoring (HTTPS), email/SMS alerting on deviation thresholds, and automated report generation compliant with FDA 21 CFR Part 11 requirements—including electronic signatures, operator authentication, and immutable log files. Calibration traceability is maintained through NIST-traceable RTD sensors (Class A, ±0.15°C accuracy at 0°C) with annual verification logs retained within the controller’s secure archive.

Applications

• Automotive: Whole-vehicle cold soak and hot soak testing; battery thermal management validation; HVAC performance assessment under climatic extremes.
• Energy Storage: BESS cabinet cycling (IEC 62619, UL 1973); thermal runaway propagation studies; long-duration calendar aging at elevated humidity.
• Aerospace & Defense: Environmental screening of radar transceivers, flight control modules, and UAV airframes per DO-160G Section 4/5/6.
• Data Center Infrastructure: Thermal stress testing of 19″ rack-mounted UPS systems, cooling distribution units (CDUs), and liquid-to-chip heat exchangers.
• Electronics Manufacturing: HASS (Highly Accelerated Stress Screening) and HALT (Highly Accelerated Life Testing) of industrial controllers, power converters, and medical imaging subsystems.
• Materials Science: Multi-sample polymer aging, coating adhesion evaluation, and composite moisture absorption kinetics under controlled RH gradients.

FAQ

What is the standard warranty period for the OK STH-4.2m² chamber?
The unit carries a 24-month parts-and-labor warranty from commissioning date, covering refrigeration components, control hardware, and structural integrity under normal operating conditions.
Can the chamber be configured for rapid temperature transition (e.g., 10°C/min)?
Standard configuration supports 1.0–4.0°C/min heating; rapid thermal transition requires optional LN₂ injection system and reinforced compressor staging—quoted separately based on target ramp rate and dwell stability requirements.
Is on-site installation and commissioning included?
Yes—OK Instruments provides full turnkey service including foundation verification, panel assembly, refrigerant charging, sensor calibration, IQ/OQ documentation, and operator training.
How is humidity controlled below 0°C?
Sub-zero humidity control is not feasible via conventional steam generation; for tests requiring low-temperature dry environments, the chamber operates in dehumidified mode using deep-cooling condensation combined with desiccant-assisted drying (available as add-on module).
Does the controller support third-party SCADA integration?
Yes—the PLC features Modbus TCP and OPC UA server functionality, enabling seamless bidirectional communication with Siemens PCS7, Rockwell FactoryTalk, or custom LabVIEW-based monitoring systems.